Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
169 Cards in this Set
- Front
- Back
|
How does pH affect enzymes? |
Enzymes working in extremes of pH above and below the optimum can denature and tertiary structure unfolds. Leads to fewer ES complexes forming. |
|
|
How does humidity affect plants and animals? |
Affects transpiration rate in plants and rate of evaporation in animals (sweating/panting). |
|
|
How can you collect a random sample? |
Produce a grid and select co-ordinates using a random number generator. Place a quadrat at the intersection of each pair of co-ordinates and record the frequency of species in it. Calculate a mean and then scale up the entire area. |
|
|
How do you decide the number of quadrats to use in order to collect representative data? |
- Large number of quadrats so results are more reliable (with repeats), - Enough to be able to carry out a statistical test (e.g. SR requires minimum of 5 pairs), - Not too many for the available time, - Calculate a running mean which changes little when there are enough quadrats (a graph of number of quadrats versus number of species would plateau) |
|
|
Name the assumptions of mark-release-recapture techniques. |
- Proportion of marked to unmarked in the second samples if equal to the proportion of marked to unmarked in the whole population, - Marked individuals from first sample distribute themselves evenly with enough time to do so - Population has a boundary so no emigration/immigration - Few deaths and births - Method of marking does not make it more liable to predation |
|
|
Name the effect of predator-prey relationship on population size.
|
Predators eat prey and reduce the prey population,
Predators now in greater competition for food, Predator population is reduced as some individuals cannot compete, Fewer prey are eaten, Prey population increases, More prey for food so predator population increases |
|
|
Describe a stable population. |
Birth rate and death rate in balance; no increase or decrease in population size |
|
|
Describe an increasing population. |
High birth rate; gives a wider base to the pyramid; fewer older people; so narrower apex |
|
|
Describe a decreasing population. |
Lower birth rate; so narrower base; more older people; wider apex |
|
|
How is NADP produced? |
NADP accepts a hydrogen ion and electron from photolysis/breakdown of water using light energy. |
|
|
Define a species. |
A group of closely related individuals which are capable of interbreeding and producing fertile offspring. |
|
|
Define a population. |
All the individuals of a given species living together in the same area at the same time. |
|
|
Define a community. |
All the individuals of a given species living together in the same area at the same time. |
|
|
Define a habitat. |
The place where an organism lives within an ecosystem. |
|
|
Define a niche. |
A niche describes where an organism lives and what it does (its role).This includes what it feeds on and how it interacts with other organisms and the environment. |
|
|
Give an advantage of organisms having different niches. |
It reduces competition between the organisms. |
|
|
Define an abiotic factor. |
A non-living factor which affects the distribution of an organism . |
|
|
Define a biotic factor. |
A living factor which affects the distribution of an organism. |
|
|
Give 4 examples of abiotic factors. |
Temperature Light pH Humidity |
|
|
Give 3 examples of biotic factors. |
Competition between organisms Predation Disease |
|
|
Define the abundance of a species.
|
Estimating the population size of each species. |
|
|
What are the three factors which you must consider when estimating population size? |
1. Random sample 2. Large sample 3. Appropriate for the species being measured |
|
|
Why is it important that samples are collected at random? |
To avoid bias |
|
|
Why is it important that a large sample size is collected? |
To ensure that the data collected is representative. |
|
|
How can you improve the reliability of the data? |
Carrying out repeat measurements. |
|
|
How can the results of an investigation be considered reliable? |
If they can be repeated. |
|
|
Define a quadrat. |
A frame of a known area which is placed on the ground and an estimate of the population sizes within the quadrat are made. |
|
|
Which three ways can the abundance of a species within a quadrat be determined? |
- Actual count of individuals present (population density). - Percentage cover - Frequency (eg is a species if found in 30 out of 100 quadrats, its frequency is thought to be 30%) |
|
|
What is a problem with using population density to determine the abundance of a species? |
- Time consuming - Some species may be difficult to count (eg grass grows in clumps..what is one plant?) |
|
|
What are the advantages of using percentage cover to determine the abundance of a species? |
Can be collected rapidly No need to define individual plants |
|
|
What is a disadvantage with of using percentage cover to determine the abundance of a species? |
- Over-layering of species may occur (stratification) so the total percentage cover may be more than 100% |
|
|
What is a point frame quadrat? |
- Used in dense vegetation - Place randomly and then pins are lowered - The species touching the pins are recorded - Species frequency is recorded as the percentage of pins that the species touches |
|
|
Why is random quadrating done? |
- To find out what species are present and their relative abundance - To compare the species abundance in two different areas - To compare the species abundance at one site at different times |
|
|
Describe a random sampling method. |
1. Two measuring tapes are arranged at right angles to each other to form the axes of a grid. 2. Obtain a series of coordinates by using random numbers generated using a table, calculater or computer. A quadrat is placed at the intersection of these coordinates. 3. Abundance is then estimated. |
|
|
Name three ways in which abundance can be estimated. |
1. Measuring population density (count total no. of individuals in a quadrat area, for number of samples and calculate density per metre squared). 2. Frequency (count number of hits in quadrat area, and calculate average frequency per metre squared). 3. Percentage cover |
|
|
Define a transect. |
A line across an area and sampling is performed at set predetermined intervals along the line (eg, every 5 metres). |
|
|
Give three examples of what sampling could include (in reference to transects). |
1. Recording what species are touching the line at each sampling point. 2. Placing two parallel lines across, a metre apart and recording what species are found between the two lines (belt transect). 3. Interrupted belt transects can be done by using one line and placing a quadrat down at equally placed sampling points and recording abundance of species within each quadrat. |
|
|
Why do we use mark-release-recapture instead of quadrats? |
For animals that move. |
|
|
Describe the mark-release-recapture method. |
1. Animals of a particular species are collected (usually by a netting or trap technique) and counted. 2. The animals are then marked in some way (dots, tags). 3. Animals are then released and left to redistribute into the population. 4. A second capture is carried out and the total number caught is recorded, as well as how many are marked. 5. Population size is then calculated: N1 x N2 / Nm N1 - number caught the first time N2 - number caught the second time Nm - number caught the second time which were marked |
|
|
What things should be considered when using a mark-release-recapture? |
1. Population size doesn't change between the capture times (few births or deaths). 2. Marking should not make the marked animals more susceptible to predators. 3. Marking should not rub off or be lost. 4. No 'trap happy' or 'trap shy' individuals. 5. Sufficient time should be left for the released to full disperse through the rest of the population. |
|
|
How do high temperatures affect populations? |
- Affects enzymes in the organism and thus its overall metabolism. - Enzymes may start to denature an the overall activity will decrease, reducing ability to survive. - Population may also experience problems with excess water loss and dehydration. |
|
|
How do low temperatures affect populations? |
- Enzymes do not have enough kinetic energy to catalyse reactions quickly enough. - Organisms overall activity will drop and may not be sufficient for survival. |
|
|
How can mammals maintain body temp? |
Endotherms (birds and mammals) can use physiological mechanisms to maintain their body temperature at a constant level (e.g. sweating, shivering). |
|
|
What can happen to a mammal as a temperature gets more extreme? |
The more extreme the temperature, the more energy the organism needs to expend to maintain its temperature and therefore the less energy available for growth and general activity. |
|
|
How can the number of species in an area change depending on the temperature? |
The more extreme the temperature, the fewer the species that can survive. For those species that do survive, the more extreme the temperature, the smaller the population size. |
|
|
How can temperature be measured? |
Using a thermometer or data logger with a temperature probe. |
|
|
How does light intensity affect photosynthesis? |
Rate of photosynthesis increases as light intensity increases. Plants grow faster and produce more spores/seeds (population will grow). Animal population that feeds on producers can grow larger. |
|
|
How does light intensity affect water? |
Water rapidly absorbs light - therefore light does not penetrate to any great depth. This will affect the level at which you find different seaweed etc. |
|
|
How do organisms tend to lose water? |
Via evaporation although it can be used for various processes, such as thermoregulation (due to sweating) or movement of mineral salts and water through the xylem. |
|
|
What happens when the humidity of the environment decreases? |
The lower the humidity of the environment, the more water loss will occur. However different species have different tolerances to this water loss. |
|
|
How can humidity be measured? |
Using a whirling hygrometer or a data logger with humidity probe. |
|
|
How does pH affect an environment? |
Can affect extracellular enzymes and surface proteins. May also affect the availability of mineral salts in the soil and therefore can affect the growth of plants. |
|
|
What can happen to an environment as pH gets more extreme? |
The more extreme the pH, the more an organism will be affected and the lower the population size and range of species present. |
|
|
What can happen to an environment as abiotic factors get more extreme? |
The more extreme these factors are, the fewer the number of species that can tolerate them and the smaller the population sizes will be. |
|
|
How does competition affect an environment? |
The more competing individuals present, the greater the competition for the resources will become. Competition regulates population sizes because it affects birth and/or death rate. |
|
|
Define intra-specific competition. |
Between members of the same species. |
|
|
Define inter-specific competition. |
Between members of different species. |
|
|
Which type of competition is more fierce? |
Intra-specific as members of the same-species have exactly the same resource requirements. |
|
|
What happens if two species occupy the same niche? |
One species tends to out-compete the other. Eventually the niche will be occupied by only the one species (competitive niche exclusion principle). |
|
|
Define predation. |
Refers to one animal species (the predator) feeding on another animal species (the prey). It normally involves the predator capturing and killing the prey. |
|
|
Name some examples of evolved mechanisms that predators have developed to help capture prey. |
High speed Venomous secretions |
|
|
Name some examples of evolved defence mechanisms that prey have developed to help avoid predators. |
Camouflage Protective spines |
|
|
How are the populations of predator and prey linked? |
As the prey population increases, there is more food for the predators and intra-specific competition is reduced. The population of the predator increases. More and more of the prey are consumed, so the prey population falls. Intra-specific competition now increases in the predator population starts to reduce again. The prey population starts to recover and the cycle starts again. |
|
|
Define succession. |
A series if changes that occur in a community over time. Succession begins on bare rock/soil/water/sand and ends with a climax community. |
|
|
Describe an environment at the start of succession. |
- Hostile - Few organisms have adaptations that enable them to survive the harsh conditions (pioneer species). |
|
|
How do environments change due to succession? |
Organisms change the environment to make the abiotic conditions less harsh. This allows other organisms to become established and replace the original pioneers. If left undisturbed for long enough, this replacement of species continues as the abiotic environment becomes less harsh until eventually a climax community is reached. |
|
|
Define a pioneer species. |
The organisms that first colonise an area (e.g. marram grass in sand dune ecosystems). |
|
|
Define sere. |
A complete succession from pioneer community to climax community. A seral stage is a particular stage in this succession with its own distinctive community of organisms. |
|
|
Define a climax community. |
The final stage in an ecological succession. A climax community is stable and changes very little. The type of community formed depends to a large extent on the climate. In much of the south of Britain it is woodland; north is more likely to be pine woodland. |
|
|
Define hostility. |
How extreme abiotic factors are in the environment. |
|
|
Define diversity. |
The relationship between the number of individual organisms of a species and the number of species within a community. A diverse community will have a wider range of species and a greater number of individuals of each species present than a less diverse community. |
|
|
Describe how abiotic factors can impact a hostile environment. |
Abiotic factors are unfavourable (extreme). Few species survive in these conditions. Diversity is low and abiotic factors dominate the distribution of species. |
|
|
Describe how abiotic factors can impact a less hostile environment. |
Abiotic factors are less harsh and diversity is higher. Biotic factors affects the distribution and abundance of organisms. |
|
|
Describe high diversity. |
High diversity is associated with a stable ecosystem and a complex food web. If the population of one species in the ecosystem drops then others will be able to increase in numbers and fill the niche so that the community is not affected that much by change. |
|
|
Describe low diversity. |
Low diversity is associated with an unstable ecosystem and a less complex food web. If one species dies out then the whole ecosystem may be disrupted. E.g. Marram grass on sand dunes - any factor that causes the death of marram grass will disrupt the whole sand dune community. |
|
|
Where does primary succession occur? |
In an environment of new substrate, which is devoid of vegetation and usually lacks soil. |
|
|
Give an example of primary succession. |
- Colonisation of bare rock. - The pioneer community is lichens and as they die and decompose they provide enough nutrients to support a community of small plants such as mosses. - As the mosses die and decompose, they are typically replaced by ferns. - With the erosion of rock and increasing amounts of organic material, a larger layer of soil is gradually built up. - This allows plants such as grasses and small flowering plants to grow, and are followed by shrubs and tress. - The climax community, in this case, is a woodland. This is a stable community of plants and animals. |
|
|
Where does secondary succession occur? |
After a forest fire or clearance of agricultural land. |
|
|
Describe secondary succession. |
Spores, seeds and vegetative organs remain visible (living) in the soil and there will be an influx of animals and plants through migration and seed dispersal from the surrounding areas. Secondary succession doesn't begin with a pioneer species but with species from intermediate seres. |
|
|
Give an example of secondary succession. |
- Australian Outback (forest fires regularly destroy the forested areas) - After only a few days small plants take advantage of the absence of the forests to grow. - In time they are replaced by shrubs which are replaced by, or are eventually joined by re-grown or new trees to restore the climax community to its original state. |
|
|
What is the aim of conservation? |
To maintain the biodiversity around us by protecting habitats, the variety of species that live there and the genetic diversity within each species. |
|
|
What is deflected succession? |
- Occurs when the climax community is prevented from establishing, as a result of, for example, management practises by humans. |
|
|
Give an example of deflected succession. |
- Woodlands will not develop on a sheep-grazed hillside, for example, and areas such as the South Dawns would disappear very rapidly if sheep were prevented from grazing the area. - The community which is maintained under such conditions is known as a plagioclimax |
|
|
Give an example of conservation. |
Seed banks - a store of seeds from different plant species in case any become extinct. Captive breeding - animals bred in captivity that are extinct in the wild or at risk of becoming extinct. Fishing quotas - reducing the number of fish that are caught and killed to reduce the threat of extinction. Protected areas - national parks and nature reserves which protect habitats by restricting development and farming. |
|
|
What is the main route that energy enters an ecosystem? |
Photosythesis |
|
|
What starts a food chain? |
Producers |
|
|
Define autotrophic. |
Anything in a food chain that can build up organic compounds from simple molecules. |
|
|
Define heterotrophic. |
Anything in a food chain that relies on an external source of organic compounds. i.e. they have to take in organic compounds by feeding on other organisms. |
|
|
Define the order of a food chain. |
Primary consumers eat producers. Secondary consumers eat primary consumers. Tertiary consumers eat secondary consumers. |
|
|
Define decomposers. |
Decomposers break down complex organic compounds in dead organisms releasing minerals and nutrients that can be absorbed by plants. |
|
|
Give an example of decomposers. |
Also know as saprobionts; e.g. bacteria and fungi |
|
|
Define a food chain. |
Shows the flow of energy in a feeding relationship and typically has no more than 4 or 5 links. Each organism represents a trophic level or feeding stage. Decomposers are often not represented on a food chain. |
|
|
Define a food web. |
Food chains do not occur in isolation and in a particular habitat, many food chains can be linked together to form a food web. |
|
|
What does a higher biodiversity mean for a food web? |
The higher the biodiversity the more complex a food web and this means that any one change in the food web will have less of an effect. |
|
|
Describe how energy is transferred between trophic levels. |
The sun is the source of energy absorbed by the producers to enable photosynthesis to occur. If the producer has consumed some of this energy it is transferred to the primary consumer - the next trophic level. This continues through each trophic level of the food chain and each stage some energy is lost. |
|
|
Why is photosynthesis an ineffective way of transferring energy from the sun? |
Only about 1-3% of available sunlight energy is trapped in photosynthesis and converted to chemical energy. |
|
|
How is sunlight lost in photosynthesis? |
- Some of the light is reflected - Some of the light may be absorbed by the atmosphere - Some of the light is the wrong wavelength - Some light does not fall on the chloroplasts and misses the chlorophyll |
|
|
Define Gross Primary Production (GPP). |
Energy which is converted into organic molecules. |
|
|
Define Net Primary Production (NPP). |
Energy which is stored or forms a new biomass. |
|
|
How is energy lost between the producer and the primary consumer? |
- Large amounts of the plant may be indigestible (some of the NPP therefore passes out as faeces). - Not all of the plant may be eaten. - Some of the energy is lost in excretion such as energy lost in urine. - Energy lost in respiration and as heat to the environment. |
|
|
How can you calculate NPP? |
GPP - R (respiration) |
|
|
How can you calculate the net production of consumers? |
I - (F + R) I = chemical energy stored as ingested food. F = chemical energy lost in faeces and urine R = respiratory losses |
|
|
How is energy lost between primary and secondary consumers? |
- Large amounts of the animal may be indigestible. - Not all of the animal may be eaten. - Some energy is lost in excretion such as energy lost in urine. - Energy lost in respiration and as heat to the environment. |
|
|
Why are food chains usually 4-5 trophic levels? |
Energy transfer in food chains is inefficient and results at large losses at each trophic level. There cannot be more than 4-5 trophic levels as there is not enough energy to support a breeding population at a higher trophic level. |
|
|
How can you calculate the percentage efficiency of energy transfer? |
Energy available after transfer/energy available before transfer x 100 |
|
|
Define a pyramid of energy. |
Considers the energy utilised in a given area at a given time so the bars represent the energy at each trophic level. |
|
|
What does the producer bar in a pyramid of energy represent? |
The light energy converted to chemical energy in photosynthesis. |
|
|
Why is a pyramid of energy more reliable than biomass? |
The bars representing consumers are more reliable than biomass as biomass could be equal but different compounds may store different amounts of energy; e.g. 1g of fat stores twice as much energy as 1g of carbohydrate. |
|
|
What are the units used in a pyramid of energy? |
Kj m-2 year-1 |
|
|
Define a pyramid of biomass. |
Shows the total mass of carbon or dry mass of tissue in a specific area at a given time. |
|
|
Why do we measure dry mass in biomass? |
Fresh mass can be measured but it is unreliable as the water content varies so it is important to use dry mass per given area (g m-2); where a volume is given the units are (g m-3). |
|
|
Why is dry mass hard to measure? |
Dry mass involves killing organisms so the samples tend to be small and this will also affect the reliability. |
|
|
Why is biomass unreliable? |
The biomass measured only represents the situation at a given point in time and does not take into account any changes at different times of the year. |
|
|
What is biomass at any one point in time called? |
The standing crop |
|
|
Why may a pyramid of biomass be inverted? |
In marine ecosystems the pyramid of biomass may be inverted as phytoplankton (producers) could at any point have less biomass than the primary consumers. Over the course of the whole year the biomass of the phytoplankton would exceed the mass of the primary consumers. |
|
|
How can chemical energy stored in dry mass? |
- Estimated using calorimetry. - Sample of dry material is weighed - Sample is burnt in pure oxygen in a sealed chamber surrounded by a water bath. - The heat of combustion causes the temperature of the water to increase. - The heat required to increase the temperature of 1g of water by 1 degree is one calorie. |
|
|
How can a farmer reduce the number of pest's and weeds? |
- Use chemical agents such as pesticides/herbicides - Biological agents such as parasites (natural predator) that kill off or limit the function of the pest. - By combining both these methods farmers can reduce pest numbers more than using one method alone. |
|
|
How does removing pests and weeds increase the amount of energy passed onto each trophic level? |
Fewer pests means less biomass is lost and crop productivity increases with more energy available to the next trophic level. Fewer weeds means there is less competition for resources (i.e. light, mineral ions, water) and crop productivity increases. |
|
|
Define intensive rearing of livestock. |
Involves controlling the condition the animals live in to reduce respiratory losses. With a reduction in respiratory losses more energy is available for growth - leading to an increase in biomass and more energy can be passed onto the next trophic level. |
|
|
How can you control the conditions an animal lives in? |
- Less movement - more muscle contraction. - Warmer environment - reduces heat loss. - Feeding - optimum amount/type to maximise growth without taste. - Predators are excluded - removes other organisms in the food web. |
|
|
Define photosynthesis. |
Photosynthesis is a process in which plants absorb light energy and convert it to chemical potential energy. Simple inorganic molecules are converted into organic molecules. |
|
|
Where is the site of photosynthesis? |
Chloroplasts |
|
|
Describe the equation for photosynthesis. |
Carbon dioxide + water = Glucose + oxygen 6CO2 + 6H2O = C6H12O6 +6O2 |
|
|
Where does the LDR stage take place? |
In the grana |
|
|
What results from the LDR stage of photosynthesis? |
The formation of ATP and a reduced hydrogen carrier (NADPH) |
|
|
Describe stage 1 of the LDR of photosynthesis. |
Light energy hits the chlorophyll molecules. Electrons in the chlorophyll gain energy, the chlorophyll loses electrons (photoionisation). |
|
|
Describe stage 2 of the LDR of photosynthesis. |
Electrons are taken up by an electron carrier (found in the thylakoid membrane which becomes reduced). The electrons then pass along the ETC in a series of oxidation and reduction reactions. The electrons lose energy at each stage of the ETC. |
|
|
Describe stage 3 of the LDR of photosynthesis. |
This energy is used to actively pump protons from the stroma to the thylakoid space. The increasing levels of protons in the thylakoid pace create a higher concentration compared to the stroma, protons move across the thylakoid membrane through the enzyme ATP synthase. As the proton passes through the enzyme it catalyses the formation of ATP from ADP and inorganic phosphate - chemiosmotic theory. |
|
|
Describe stage 4 of the LDR of photosynthesis. |
At the end of the second ETC the protons and electrons combine to reduce a hydrogen carrier NADP to form NADPH. Oxygen is given off as a waste product. |
|
|
Where does the LIR take place? |
In the stroma |
|
|
What does LIR require? |
ATP & NADPH from the LDR Does not require light |
|
|
Describe the calvin cycle. |
Co2 diffuses into the leaf through the stomata, RuBP acts as the carbon dioxide acceptor. The Co2 reacts with the RuBP to form two molecules of GP catalysed by the enzyme rubisco. GP is reduced to TP; this requires NADPH which provides the reducing power (H) and the energy from the hydrolysis of ATP - NADP, ADP and Pi go back to LDR. |
|
|
What happens to the leftover TP during the calvin cycle? |
Some of the TP is converted to useful carbohydrates, amino acids, triglycerides. Most of the TP us used to regenerate RuBP. |
|
|
What are the limiting factors for photosynthesis? |
- Light intensity - Temperature - CO2 concentration - Water |
|
|
Why is light intensity a limiting factor for photosynthesis? |
Light is needed to provide the energy for photoionisation of the chlorophyll. The higher the light intensity the more energy is provided. Not all wavelengths of light are required as only red and blue light from sunlight are absorbed. |
|
|
How can knowledge of limiting factors be used commercially? |
- Growers can apply knowledge of limiting factors to enhance temperature, co2 concentration and light intensity. - Manipulation of these factors may increase productivity and therefore produce higher yields. |
|
|
How are glasshouses used commercially? |
Glasshouses can be used to grow crops in areas where the crop cannot grow (e.g. England) and to be grown all year round. |
|
|
How can light as a limiting factor be used in glasshouses? |
Artificial light may be used to increase light intensity to the optimum level. Blinds may be used to shade plants if light intensity is very high as very high light intensity can damage chlorophyll. |
|
|
How can carbon dioxide as a limiting factor be used in glasshouses? |
Carbon dioxide levels can be increased by burning fossil fuels (e.g. paraffin heaters) or pumping co2 into the glasshouse. |
|
|
How can temperature as a limiting factor be used in glasshouses? |
Heaters can be used to raise the temperature to optimum levels, also used as night to prevent temperatures falling to levels where plants may be damaged. |
|
|
Describe the equation for respiration. |
Glucose + oxygen = carbon dioxide + water
C6H12O6 +6O2 = 6CO2 + 6H2O |
|
|
Why is glucose not an immediate energy source in cells? |
The energy released from glucose is used to form ATP which is the immediate energy source; ATP is broken down to ADP + Pi in a single step reaction releasing small useable amounts of energy. |
|
|
Define aerobic respiration. |
Requires oxygen and results in carbon dioxide and water in animals. |
|
|
Define anaerobic respiration. |
Takes place in the absence of oxygen and results in producing lactic acid in animals and ethanol in plants. |
|
|
Where does respiration occur? |
Mitochondria |
|
|
What are the main stages of aerobic respiration? |
1. Glycolysis (cytoplasm) 2. Link reaction (matrix of mitochondria) 3. Kreb's cycle (matrix of mitochondria) 4. Electron transport chain (mitochondrial membranes) |
|
|
What is the process called when ATP can be generated directly in respiration? |
Substrate phosphorylation |
|
|
When else is ATP produced during respiration? |
Many of the reactions in respiration involve oxidation and reduction. ATP is generated when H is lost and used to reduce substances called H carriers or co-enzymes. The reduced H carriers or coenzymes is a source of chemical energy and can be used to generate ATP by oxidative phosphorylation. |
|
|
Describe glycolysis. |
- Occurs in the cytoplasm of the cell 1. Glucose is activated by phosphorylation (requires hydrolysis of ATP to provide the phosphate) 2. Phosphorylated glucose is then split into two triose molecules 3. Triose phosphates (TP) are then oxidised to pyruvate (involves the loss of H which reduces NAD -also produces ATP) |
|
|
What does glycolysis yield? |
2 ATP directly 2 reduced NAD (which also produce ATP by oxidative phorylation) 2 molecules of pyruvate |
|
|
How does pyruvate move into the mitochondrial matrix? |
Active transport |
|
|
Describe the link reaction. |
- Occurs in the mitochondrial matrix 1. Pyruvate is oxidised to acetate (hydrogen lost reduces NAD) 2. Acetate combines with coenzyme A to produced acetyl coenzyme A (loses a molecule of carbon dioxide) 3. No ATP produced |
|
|
What does the link reaction yield? |
- 2 reduced NAD molecules - 2 molecules of acetyl coenzyme A |
|
|
Describe the kreb's cycle. |
Acetyl coenzyme A is fed into a series of oxidation and reduction reactions which occur in the matrix of the mitochondria. |
|
|
What does the kreb's cycle result in? |
- Carbon dioxide is produced - Some ATP is produced directly - Loss of H which reduces H carriers NAD and FAD and will be used to produce ATP in oxidative phosphorylation. - This occurs for both molecules of acetyl coenzyme A. |
|
|
Describe the electron transport chain. |
- The reduced hydrogen carriers produced in glycolysis, the link reaction and kreb's cycle will produce ATP by oxidative phosphorylation. |
|
|
Where does the electron transport chain occur? |
Mitochondrial membranes |
|
|
How is ATP formed by oxidative phosphorylation during the electron transport chain? |
- Reduced H carriers are oxidised to hydrogen - Electrons from the hydrogen pass down a series of electron carriers on the mitochondrial membrane in a series of REDOX reactions - As electrons pass along the ETC they lose energy, some of which is used to pump the H+ (protons) through the inner membrane into the space between the inner and outer mitochondrial membrane - H+ pass back through the inner membrane via ATP synthase enzymes and as they pass through the enzymes enough energy is released to form ATP - chemiosmotic theory |
|
|
What are the waste products of the electron transport chain? |
Some of the energy lost as the electrons pass along the ETC is lost through heat. The electrons and H+ combine with oxygen to form water, oxygen is the final electron acceptor. |
|
|
What processes stop during anaerobic respiration? |
The link reaction Kreb's cycle Electron Transport Chain |
|
|
Why does glycolysis continue during anaerobic respiration? |
Glycolysis does not require oxygen and can continue in the absence of oxygen but con only continue if NAD is regenerated. |
|
|
How is NAD regenerated during anaerobic respiration? |
The H from the reduced NAD is now accepted by pyruvate rather than passing through the ETC. The pyruvate is reduced to lactate in animals and ethanol in plants. |
|
|
How much ATP per molecule of glucose is produced during aerobic respiration? |
38 molecules. |
|
|
How much ATP per molecule of glucose is produced during aerobic respiration? |
2 molecules |
|
|
Define chemiosmosis. |
As electrons are passed from NADH to an electron carrier protein from the H+, protons are actively transported across the inner mitochondrial membrane via membrane proteins. Protons accumulate in the space between the two mitochondrial membranes to create a proton gradient. Protons then diffuse back into the matrix via ATP synthase. |
|
|
Define photophosphorylation. |
Occurs in chlorophyll containing cells during photosynthesis (energy ultimately comes from light) |
|
|
Define oxidative phosphorylation. |
Occurs on the ETC on the inner mitochondrial membrane (during the last part of respiration) - synthesis is driven by energy transferred from a proton gradient. |
|
|
Define substrate level phosphorylation. |
Where phosphate groups are transferred from donor molecules (e.g. during the first part of respiration) into the the cytoplasm of the cells. |
|
|
What type of cells are very metabollically active? |
Muscle cells Epithelial cells of the small intestine |
